In a mixing bowl, whisk together cinnamon, baking soda, baking powder, salt, and flour. Set aside.
Cream together butter and sugars in a large mixing bowl using a hand mixer.
Add eggs and vanilla, and beat until batter is fluffy.
Beginning and ending with the buttermilk, rotate adding the buttermilk and flour mixture until fully combined and fluffy.
Mix in mashed bananas until combined.
Prepare two 9-inch round pans by lining the bottom with parchment paper and spraying with non-stick cooking spray.
Divide batter between the two cake pans.
Bake for 35 to 40 minutes or until a toothpick inserted in the center of the cake comes out clean.
Remove pans and cool for 15 minutes. Gently remove cakes from pans to cooling racks and cool completely.
Frosting
Beat together softened cream cheese, butter, and vanilla until fully combined.
Add in powdered sugar and beat until smooth, the mixture will be thick.
Drizzle heavy cream into frosting mixture while beating until frosting is fluffy and to a spreadable consistency.
Assembly
Trim the top of each cake layer to remove any doming and form a flat surface.
Place first cake layer top side up onto serving platter.
Mound about ½ cup of frosting onto the cake layer and spread smooth to the edges.
Place the second cake layer top side down on top of the filling. Press down gently to seal the layers together.
Mound another pile of frosting on top of the cake and use a spatula to spread it across the top and down the sides until cake is fully frosted.
Decorate with banana slices (dip banana slices in lemon juice to prevent browning) or however you’d like.
Refrigerate or freeze until ready to serve.
Video
Notes
You can make your own buttermilk using whole or 2% milk and lemon juice or distilled vinegar. For every 1 cup of milk, stir in 1 tablespoon of lemon juice or vinegar.
If you want taller cake layers, use smaller cake pans such as a 7-inch or 8-inch size.
Oven temperatures vary and may need to be recalibrated periodically to ensure they are accurate. Make sure to check your cake at the lower end of the recommended baking time.
Make sure your cream cheese is at room temperature to ensure it blends fully with the rest of the ingredients and doesn't leave lumps.